Information recording apparatus

ABSTRACT

An information recording apparatus includes an energy generation device for generating recording energy; a position control device for controlling a position of irradiation on the recording medium with an output of the energy generation device; a drive device for driving the energy generation device; a switching device for switching information based on user data and test information to supply the two kinds of information selectively to the drive device; a reading device for reading the marks recorded on the recording medium; an evaluation device for evaluating a reproduced signal obtained by the reading device; and a recording condition control device for controlling a recording condition on the basis of an evaluation result obtained by the evaluation device, wherein, when the marks used for recording the test information are to be reproduced, controlling operation of the position control device is changed to be different from that used for recording the test information.

CROSS REFERENCES TO RELATED APPLICATIONS

[0001] This is a continuation of application Ser. No. 09/583,480 filedMay 31, 2000.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an information recordingapparatus for recording information by a local physical change in arecording medium due to energy irradiation, and exclusively relates toan optical disk device.

[0004] 2. Description of the Related Art

[0005] Currently available optical disk-medium and device combinationscan be roughly classified into a combination of magneto-optical disksand a magneto-optical disk device of the type of forming a mark by areversal magnetic domain on a recording layer by heating the recordinglayer, and a combination of phase-change disks and an optical diskdevice of the type of forming a mark by an amorphous domain on arecording layer while changing the cooling speed of the recording layerby controlling the quantity of recording energy input at heating. As anexample of a method for improving recording density of information to berecorded on such recording media, there is a method in which marksholding information are reduced as a whole and, at the same time, thedistance between adjacent marks is shortened. In either type, it is,however, essential that the mark shape is controlled accurately. Thatis, if the mark length along a scanning direction of optical spot(tracking direction) is too short, jitter of a reproduced signalincreases so that reliability of reproduced information cannot besecured. If the mark length along the tracking direction is contrariwisetoo long, jitter of the reproduced signal also increases. If the markwidth along a direction perpendicular to the scanning direction(perpendicular to tracks) of optical spot is too narrow, the amplitudeof the reproduced signal decreases so that reliability of reproducedinformation cannot be secured. If the mark width in the perpendiculardirection is contrariwise too wide, crosstalk in reproduction processwith respect to adjacent tracks increases so that reliability ofreproduced information cannot be secured and, accordingly, there is arisk of cross-erase that adjacent recorded marks may be destroyed whenthings come to the worst. As described above, there is an importanttheme in terms of improvement of recording density of such recordingmedia that a mark holding is formed into a desired shape (length andwidth) which is neither too large nor too small.

[0006] It is, however, very difficult to form stably and accurately asmall mark having a size not larger than about a half of the opticalspot size when the mark is to be reduced in size for the sake ofhigh-density recording. This is because such a small mark cannot but beformed stably in a spatially gentle temperature gradient portion whichis near a peak temperature portion among temperature rise portions ofthe recording layer by the optical spot. Hence, the peak temperature ina recording mode varies for every mark because of the change of thetemperature of the recording layer before recording energy irradiationand the change of the intensity of recording energy. That is, theeffective recording sensitivity of the recording layer varies. As aresult, the mark shape varies greatly. In the case of an optical disk ofthe type of controlling the mark shape by recording energy intensitywaveform, the peak temperature of the recording layer is apt to varyparticularly due to variation of thickness of the recording layer of therecording medium and in accordance with the recording pattern. Reductionof the diameter of the optical spot by use of a short wavelength laserlight source is direct to solve the aforementioned problem. Reduction ofthe wavelength of a semiconductor laser diode which is a typical laserlight source is, however, attended with technical difficulty. Hence,there is the existing state of affairs that no technique has satisfiedthe demand for increase of recording density.

[0007] To solve these problems, in JP-A-5-298737 (hereinafter referredto as a first related art), a test-write zone is provided on a recordingmedium so that a signal reproduced from marks recorded in the test-writezone is evaluated for the purpose of forming small marks by the sameoptical spot stably and accurately. That is, when recording is performedwhile recording power is changed, leading and trailing edges of a markshift in reverse directions along a tracking direction. The firstrelated art asserts that the recording condition (especially, recordingpower) can be optimized when the length of the mark in the trackingdirection is detected by use of the aforementioned technique.

[0008] In JP-A-1-292603 (hereinafter referred to as a second relatedart), for the same purpose as that of the first related art, amagneto-optical recording medium is heated periodically andintermittently by light pulses at regular intervals and, at the sametime, a magnetic field applied to the heated region is inverted at ahigh speed. That is, the direction of magnetization of the approximatelycircular heated region can be determined in accordance with heat byevery light pulse. Hence, when this operation is repeated while theheated position is shifted along the tracking direction, the directionof magnetization of a crescent-shaped domain can be substantiallydetermined in accordance with heat by every light pulse. The secondrelated art asserts that the mark length in the tracking direction andthe mark width in a direction perpendicular to the tracking directioncan be controlled independently so that a very small mark compared withthe diameter of the optical spot can be formed stably regardless of themark width.

[0009] The first related art, however, utilizes the characteristic ofso-called “light intensity modulation method” in which the mark shape isdetermined only by a heating procedure by means of an optical spot. Thatis, the phenomenon that leading and trailing edges of each mark shift inreverse directions when recording is performed while recording power ischanged is peculiar to the light intensity modulation method. The firstrelated art cannot be applied to a “magnetic field modulation method” ora “laser-strobe magnetic field modulation method” in which leading andtrailing edges of each mark shift by the same distance in the samedirection along the tracking direction even in the case where recordingis performed while recording power is changed. Moreover, substantiallyin the first related art, the shifting of the leading and trailing edgesof the mark caused by the change of recording power is merely detectedbut the mark width is not detected directly. Accordingly, it wasdifficult to control the mark width accurately, that is, to determinerecording power accurately. Hence, it was impossible to performrecording/reproduction using small marks at narrow track intervals, sothat the first related art was disadvantageous in terms of improvementof recording surface density.

[0010] In the second related art, a very small mark compared with thediameter of the optical spot can be formed and, at the same time, themark width and the shortest mark length can be changed individually.This effect is however effective only on magneto-optical recordingmedia. Moreover, the conventional test-write method as disclosed in thefirst related art cannot be used in the second related art becauseleading and trailing edges of each mark shift by the same distance inthe same direction along the tracking direction even in the case whererecording is performed while recording power is changed, as describedabove. Hence, it was impossible to control the mark width sufficiently,so that it was difficult to reduce the track pitch.

[0011] For the aforementioned reason, in the respective related art, itwas therefore impossible to form small marks with sufficient accuracy,so that it was impossible to improve recording surface density.

SUMMARY OF THE INVENTION

[0012] An object of the present invention is to provide an informationrecording apparatus capable of forming marks carrying information with ashape desired to enhance recording areal density.

[0013] According to an aspect of the present invention, there isprovided an information recording apparatus for recording information ona recording medium by supplying the recording medium with energy to formmarks different in physical property from non-recorded portions,comprising: a recording energy generation device for generatingrecording energy; a position control device for supplying an output ofthe recording energy generation device to a desired position on therecording medium; a drive device for driving the energy generationdevice; a switching device for switching information based on user dataand test information to supply these two kinds of informationselectively to the drive device; a reading device for reading the marksrecorded on the recording medium; an evaluation device for evaluating areproduced signal obtained by the reading device; and a recordingcondition control device for controlling a recording condition on thebasis of an evaluation result obtained by the evaluation device,wherein, when the marks used for recording the test information are tobe reproduced, controlling operation of the position control device ischanged to be different from that used for recording the testinformation.

[0014] With the aforementioned configuration, the mark width can bedetected directly to optimize the recording condition. By the recordingcondition optimizing operation, variation of the mark shape caused byvariation of recording sensitivity of the recording medium due tovariation of thickness of the recording layer of the recording medium orvariation of the environmental temperature can be reduced as extremelyas possible. At the same time, variation in the operating characteristicof the apparatus for performing recording can be reduced. Hence, a verysmall mark can be formed extremely accurately, so that improvement ofrecording surface density can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a diagram showing an example of the configuration of aninformation recording apparatus according to the present invention;

[0016]FIG. 2 is a flow chart showing a process of optimizing a recordingcondition of the information recording apparatus according to thepresent invention;

[0017]FIG. 3 is a view showing a recording/reproducing method applied toa test-write zone by the apparatus depicted in FIG. 1;

[0018]FIG. 4 is a diagram showing an example of the configuration of areproduced signal evaluation circuit corresponding to FIG. 3;

[0019]FIG. 5 is a time chart showing the operation of the reproducedsignal evaluation circuit depicted in FIG. 4;

[0020]FIG. 6 is a graph showing a reproduced signal evaluation processcontained in the recording condition optimizing process explained inFIGS. 3 to 5;

[0021]FIG. 7 is a view showing another recording/reproducing methodapplied to a test-write zone by the apparatus depicted in FIG. 1;

[0022]FIG. 8 is a diagram showing an example of the configuration of areproduced signal evaluation circuit corresponding to FIG. 7;

[0023]FIG. 9 is a diagram showing the operation of the reproduced signalevaluation circuit depicted in FIG. 8;

[0024]FIG. 10 is a view showing a further recording/reproducing methodapplied to a test-write zone by the apparatus depicted in FIG. 1;

[0025]FIG. 11 is a diagram showing an example of the configuration of areproduced signal evaluation circuit corresponding to FIG. 10;

[0026]FIG. 12 is a diagram showing the operation of the reproducedsignal evaluation circuit depicted in FIG. 12;

[0027]FIG. 13 is a graph showing a reproduced signal evaluation processcontained in the recording condition optimizing process explained inFIGS. 10 to 12;

[0028]FIG. 14 is a view showing a further recording/reproducing methodapplied to a test-write zone by the apparatus depicted in FIG. 1;

[0029]FIG. 15 is a diagram showing an example of the configuration of areproduced signal evaluation circuit corresponding to FIG. 14; and

[0030]FIG. 16 is a diagram showing the operation of the reproducedsignal evaluation circuit depicted in FIG. 15.

DESCRIPTION OF THE EMBODIMENTS

[0031] Embodiments of the present invention will be described below.Although description will be made on the assumption that the presentinvention is applied to a magneto-optical disk device using a lightintensity modulation method, it does not limit the shape of therecording medium and the recording method as a subject of the presentinvention. That is, the medium may be shaped like a tape, a card, etc.,and the recording method may be a magnetic field modulation method or alaser-strobe magnetic field modulation method other than the lightintensity modulation method. Further, the following description does notintend to limit the recording principle, and the gist of the presentinvention is also effective for an information recording apparatus basedon phase-change recording, or the like. That is, the present inventioncan be generally applied to information recording apparatuses forrecording information by energy irradiation of a recording medium tobring a local physical change of the recording medium.

[0032]FIG. 1 is a diagram showing an example of the configuration of aninformation recording apparatus according to the present invention. Inthe apparatus, respective blocks are controlled by a main controller103. The main controller 103 issues instructions concerning recordingpower to a laser drive circuit 110, instructions concerning inputselection to a recording signal switcher 102, instructions concerningmagnetic field applying direction to an electromagnet drive circuit 100and instructions concerning servo condition (focusing displacement fromfocus point, focusing on/off, polarity of tracking, trackingdisplacement from track center, tracking on/off, etc.) to a servocontrol circuit 121. In an information reproducing mode, a laser beam134 scans marks (not shown) and embossed pits (not shown) on amagneto-optical recording medium 114. Light reflected at themagneto-optical recording medium 114 is led to a photo detector 116 viaan objective lens 107 and a beam splitter 108. The photo detector 116converts the intensity distribution and polarization component of thereflected light into electric signals proportional to the intensitythereof. In a playback amplifier 117, these signals are furtherconverted into a focusing error signal, a tracking error signal, asignal of total light intensity 135 and a reproduced magneto-opticalsignal 138. The focusing error signal and the tracking error signal forma servo error signal 137 which indicates the position of an opticalspot. The servo error signal 137 is given to a servo control circuit121. Hence, the position of the objective lens 107 is controlled by anactuator 115 so that the optical spot for recording/reproduction canscan a desired position with a suitable size on the magneto-opticalrecording medium 114. In an ordinary information recording mode,recording data 105 which is user data is converted, by an encoder 104,into a record mark sequence 132 corresponding to a mark sequence formedon the magneto-optical recording medium 114. The encoder 104 has amodulation rule according to (1,7) modulation. The record mark sequence132 is transmitted to a laser drive circuit 110 through a record signalswitcher 102. In the laser drive circuit 110, the record mark sequence132 is converted into a laser drive current corresponding to the laseremission waveform, so that a laser 109 which is a recording energysource is made to emit light. The laser beam 134 emitted from the laser109 is converged onto the magneto-optical recording medium 114 via thebeam splitter 108 and the objective lens 107 to heat a recording layer(not shown) to thereby form a mark. In this mode, a recording magneticfield in a predetermined direction is applied to the position ofconvergence of the laser beam 134 by an electromagnet 106. In anordinary information reproducing mode, marks on the magneto-opticalrecording medium 114 are scanned by a laser beam 134 which is so low inlevel as not to destroy the marks. A reproduced magneto-optical signal138 corresponding to the presence/absence of a mark in an optical spotscanning position on the magneto-optical recording medium 114 issubjected to a waveform equalizing process by a waveform equalizer 118and further converted into a reproduced mark sequence 140 by a slicer119. At the same time, a PLL 112 generates a clock signal 136 on thebasis of the signal of total light intensity signal 135 and thereproduced magneto-optical signal 138. The slicer 119 uses the clocksignal 136 as a reference timing signal for restoring the reproducedmagneto-optical signal to the reproduced mark sequence 140. Finally, adecoder 120 decodes reproduced data 113 by performing the inverse of theencoder 104 with reference to the reproduced mark sequence 140 andissues the reproduced data 113 to the outside. In an information erasingmode, the laser 109 emits light continuously to heat the magneto-opticalrecording medium 114 continuously to the recording temperature orhigher. At the same time, an erasing magnetic field in a directionreverse to the direction in the information recording mode is generatedby the electromagnet 106, and applied to the position of convergence ofthe laser beam 134. In a test-write recording mode, a magnetic field inthe same direction as that in the ordinary information recording mode isapplied to the magneto-optical recording medium 114, and the actuator115 moves the optical spot position into a predetermined test-write zone(not shown) provided on the magneto-optical recording medium 114. Then,an operation different from that in the ordinary information recordingmode is carried out as follows. A test-write mark sequence 131 generatedby a test-write mark sequence generator 101 is given, in place of therecord mark sequence 132, to the laser drive circuit 110. Hence, thetest-write mark sequence 131 is recorded while the recording condition(recording power, focusing displacement from a focus point in therecording mode and tracking displacement from a center track in therecording mode) is changed in accordance with the instructions of themain controller 103. The test-write mark sequence 131 thus recorded isreproduced in the same manner as in the ordinary information reproducingmode. A reproduced magneto-optical signal 138 which is a signalreproduced from the test-write mark sequence 131 is evaluated by areproduction signal evaluation circuit 111. An evaluation result 133from the reproduction signal evaluation circuit 111 is given to the maincontroller 103. A reference timing signal 141 or 142 indicating timingrequired for evaluation is supplied from the PLL 112 or the maincontroller 103 to the reproduction signal evaluation circuit 111 asoccasion demands. The main controller 103 compares the recordingcondition with the evaluation result 133 of the reproducedmagneto-optical signal 136, determines an optimum recording conditionand controls respective portions of the apparatus on the basis of theoptimum recording condition.

[0033]FIG. 2 is a flow chart showing a process of optimizing therecording condition of the information recording apparatus according tothe present invention. First, after the apparatus is initialized byturning on a power supply, or the like, a judgment is made as to whethera recording medium has been already set in the apparatus or not. Ifthere is no recording medium, the apparatus is still in an idle state.If a recording medium has been already set, the apparatus carries out anoperation of optimizing the recording condition continuously. Theoperation of optimizing the recording condition is also started when therecording medium is exchanged to a new one, when error occurs inrecording/reproduction or when a predetermined time is passed after thecompletion of the recording condition optimizing operation in theprevious cycle, as well as when the apparatus is initialized. First, theoptical spot is moved to a predetermined test-write zone, the zone iserased, and a recording condition which has been not tried yet is setfor the respective portions of the apparatus. Then, a test-write marksequence is recorded on the erased test-write zone. Immediately afterthe recording of the test-write mark sequence, the test-write marksequence is reproduced without any change of the servo condition(focusing displacement from a focus point, tracking displacement from acenter track, polarity of tracking or tracking on/off), so that theamplitude of the reproduced signal is measured by the reproductionsignal evaluation circuit. Let the amplitude of the reproduced signal beV1 at this time. Then, the servo condition is changed, and thetest-write mark sequence is reproduced from the test-write zone again.Let the amplitude of the reproduced signal be V2 at this time. If therelation between the amplitudes V1 and V2 (for example, the ratio of V1to V2) is within tolerance, the main controller regards the record markwidth as being within tolerance and terminates the recording conditionoptimizing operation normally so that the operation is restored to therecording/reproducing operation of the apparatus itself. If the relationbetween V1 and V2 is not within tolerance, the main controller searchesfor any other recording condition to be tried. If any other recordingcondition has remained yet, the recording condition is changed to it andthe operation is returned to the erasion of the test-write zone so thata series of steps is repeated. If any other recording condition to betried has not remained, the main controller regards the recording mediumor the apparatus as being abnormal and terminates the recordingcondition optimizing operation abnormally while informing the outside ofthe abnormal termination.

[0034]FIG. 3 is a first explanatory view showing an example ofrecording/reproduction on/from the test-write zone by the apparatusdepicted in FIG. 1. Wobble pits 303 for generating a tracking servosignal by a sampled servo method and clock pits 300 for generating arecording/reproducing timing signal are formed at regular angularperiods on a disk which is a recording medium. First, in a test-writerecording mode, adjacent tracks n−1, n and n+1 are erased and thentest-write marks 302 are formed at suitable regular periods in a statein which marks are in phase among the adjacent tracks (marks come sideby side with one another and intermark gaps come side by side with oneanother). Taking into account the necessity of measuring the width of amark accurately while avoiding timing error between recording andreproduction, timing error between tracks and the influence of leadingand trailing edges of the mark at the time of detection of the markwidth, it is preferable that the length of a gap (space) betweentest-write marks 302 as viewed in a tracking direction is not smallerthan the diameter of the optical spot and as long as possible.Particularly when a light intensity modulation method is used, there isa possibility that the width of the leading edge of the mark in whichaccumulation of recording energy is not converged may be different fromthe width of the trailing edge of the mark in which accumulation ofrecording energy is converged. It is also preferable from this point ofview that the mark is set to be as long as possible to measure the markwidth accurately. Taking into account the frequency characteristic, etc.of the recording/reproducing channel, it is, however, undesirable that amark/space which is too long for recording/reproducing user dataactually is used as the test-write mark 302/space in each track. To sumup, it is most preferable that the longest mark and space allowable inthe scope of the conversion rule of the encoder 104 are used as thetest-write mark 302 and space in each of tracks n−1 and n+1. When, forexample, the conversion rule of the encoder 104 is (1,7) modulation, andinformation after conversion is subjected to mark edge recording (NRZImodulation), the length of mark/space used for recording/reproducinguser data actually is in a range of from 2 to 8 channel bits. Hence, inthis case, it is most preferable that the length of test-write mark302/space in each track is 8 channel bits. In a test-write recordingmode, the optical spot is controlled to scan the center of each track asrepresented by an on-track optical spot 301. In FIG. 3, each of thearrows denotes the scanning direction and center position of the opticalspot. Then, in a test-write evaluation mode, after reproduction isperformed in the same servo condition as in the test-write recordingmode so that the optical spot scans the center of the track, the servocondition is changed. That is, as represented by a reverse-track opticalspot 304, tracking control is performed in reversed polarity so thatintertrack reproduction is performed (reverse-track). Although the caseof reverse-track reproduction is shown now, the servo condition used maybe such that tracking displacement from a track center is applied in thesame polarity as that in the recording mode.

[0035]FIG. 4 is a diagram showing an example of the configuration of thereproduction signal evaluation circuit corresponding to FIG. 3. FIG. 5is a time chart showing the operation of the reproduction signalevaluation circuit depicted in FIG. 4. As the whole of the circuit, aclock signal 500 generated by the PLL 112 on the basis of the clock pits300 is referred to as a reference timing signal for the operation of thecircuit. A peak timing signal 401 and a bottom timing signal 402indicating the center position of the test-write mark 302 and the centerposition of the space between adjacent test-write marks respectively aregenerated on the basis of the clock signal 500 and supplied from the PLL112. First, a reproduced signal 400 such as a reproduced magneto-opticalsignal is supplied to a D/A converter 410 and digitized therein. Anoutput of the D/A converter 410 is supplied to a peak accumulator 411and a bottom accumulator 412, so that levels of the output areaccumulated on the basis of the peak timing signal 401 and the bottomtiming signal 402 respectively. These accumulation processes are usedfor performing the recording condition optimizing operation moreaccurately by reducing the influence of noise included in the reproducedsignal 400. These accumulation processes can be omitted if thesignal-to-noise ratio of the reproduced signal 400 is sufficiently high.Then, outputs of the peak accumulator 411 and the bottom accumulator 412are supplied to an on-track subtracter 414 and a reverse-trackaccumulator 413 and converted into the amplitude Von of the reproducedsignal at on-track reproduction and the amplitude Vre of the reproducedsignal at reverse-track reproduction respectively. Finally, theamplitudes Von and Vre are supplied to a divider 415, so that acalculation result after calculation of the ratio Vre/Von is transmittedas an evaluation result 403 to the main controller.

[0036]FIG. 6 is a graph showing a reproduction signal evaluation methodcontained in the recording condition optimizing method as explainedabove with reference to FIGS. 3 to 5. Recording power is optimized bythe recording condition optimizing operation in accordance with thefollowing procedure. That is, on-track reproduction and reverse-trackreproduction are performed by use of a test-write zone while changingrecording power to thereby detect the amplitude of a reproduced signalon the basis of a test-write mark. The reproduced signal amplitude Vonat on-track reproduction begins to increase at recording commencingpower and increases continuously as the mark width increases. However,after the mark width becomes approximately equal to the diameter of theoptical spot, the amplitude little changes even in the case whererecording power is increased. This is because the amplitude Von is themirror of the mark width. On the other hand, the reproduced signal widthVre at reverse-track reproduction begins to increase gradually atrecording commencing power and increases continuously as the mark widthincreases. However, after marks on adjacent tracks come into contactwith each other, the amplitude Vre is saturated with the same saturationvalue as that of the amplitude Von. This is because the amplitude Vre isthe mirror of the distance between marks on adjacent tracks. Hence, ifrecording is performed with recording power so that the ratio of Vre toVon takes a predetermined value, a mark having a constant width can beformed extremely and accurately. Hence, the distance between adjacenttracks in an optical disk can be reduced, so that the informationrecording apparatus can be improved in storage capacity and reliability.

[0037]FIG. 7 is a second explanatory view showing anotherrecording/reproducing method applied to the test-write zone by theapparatus explained above with reference to FIG. 1. On a disk which is arecording medium, grooves 705 are formed at regular intervals in aradial direction of the disk so that the grooves 705 divide a surface ofthe disk into tracks and generate a tracking servo signal by acontinuous servo method. Address pits 700 for holding addressinformation are formed at regular intervals in each track, so that eachtrack is further divided into sectors 707 as minimum rewriting units. Ina recording mode, VFO marks 701 serving as a recording/reproducingtiming reference are formed just after the address pits 700, and userdata or test-write marks 706 are formed after the VFO marks 701. First,in a test-write recording mode, adjacent tracks n−1, n and n+1 areerased. Then, test-write marks 706 are formed at suitable regularperiods on the tracks n−1 and n+1 whereas a test-write mark 706sufficiently longer than those in the tracks n−1 and n+1 is formed onthe track n. Taking into account the necessity of measuring the markwidth accurately while avoiding timing error between recording andreproduction and the influence of leading and trailing edges of eachmark at the time of detection of the mark width, it is preferable thatthe length of each test-write mark 706/space in the tracks n−1 and n+1is made to be not smaller than the diameter of the optical spot and aslong as possible. Particularly when a light intensity modulation methodis used, there is a possibility that the width of the leading edge ofthe mark in which accumulation of recording energy is not converged maybe different from the width of the trailing edge of the mark in whichaccumulation of recording energy is converged. It is preferable fromthis point of view that the mark is set to be as long as possible tomeasure the mark width accurately. Taking into account the frequencycharacteristic of the recording/reproducing channel, the followingresponse of the PLL for generating a recording/reproducing timingsignal, etc., it is, however, undesirable that a mark/space which is toolong for recording/reproducing user data actually is used as thetest-write mark 706/space in each of the tracks n−1 and n+1. To sum up,it is most preferable that the longest mark/space allowable in the scopeof the conversion rule of the encoder 104 is used as the test-write mark706 and space in each of the tracks n−1 and n+1. When, for example, theconversion rule of the encoder 104 is (1,7) modulation, and informationis subjected to mark edge recording (NRZI modulation) after conversion,the length of mark/space to be used for recording/reproducing user dataactually is in a range of from 2 to 8 channel bits. Hence, in this case,it is most preferable that the length of test-write mark 706/space ineach of the tracks n−1 and n+1 is 8 channel bits. On the other hand, thereason why a mark longer than those in the tracks n−1 and n+1 isrecorded on the track n is that the continuous servo method can hardlyadjust the recording/reproducing timing between adjacent tracksaccurately and can hardly make the marks in phase between adjacenttracks. When the test-write marks 706 on the tracks n+1 and n−1 are thelongest marks in the scope of the conversion rule of the encoder 104,the test-write mark on the track n is inevitably out of the conversionrule of the encoder 104. However, because the subject of measurement ofthe mark width is the test-write marks 706 formed on the tracks n−1 andn+1, that is, because the test-write mark 706 formed on the track n isnot the subject of measurement (reproduction), there is no problem evenin the case where the test-write mark on the track n violates againstthe conversion rule of the encoder 104 (even if the test-write mark onthe track n exceeds the run-length limitation). This causes no problemin the recording condition optimizing operation. The mark may be ratheras long as possible so that the mark extends over the whole of thesector 707. In the test-write recording mode, as represented by theon-track optical spot 702, the optical spot is (on-track) controlled soas to scan the center of each track. In FIG. 7, each of the arrowsdenotes the scanning direction and center position of the optical spot.Then, in a test-write evaluation mode, after reproduction is performedin the same servo condition as in the test-write recording mode so thatthe optical spot scans the center of the track n+1 or n−1, the servocondition is changed. That is, as represented by the de-track opticalspot 704, scanning is performed by application of tracking displacementin a downward direction in FIG. 7 with reference to the center of thetrack n+1 (de-track). Although the case of de-track reproduction isshown now, a servo condition of polarity reverse to that in thetest-write recording mode may be used.

[0038]FIG. 8 is a diagram showing an example of the configuration of areproduction signal evaluation circuit corresponding to FIG. 7. FIG. 9is a diagram showing the operation of the reproduction signal evaluationcircuit depicted in FIG. 8. First, a reproduced signal 800 such as areproduced magneto-optical signal is given to a peak detection circuit811 and a bottom detection circuit 810, and converted into a peakenvelope signal Vp and a bottom envelope signal Vb. The signals Vp andVb are given to a subtracter 812. The subtracter 812 gives the amplitudedifference Vp−Vb of the reproduced signal to an on-track S-H(sample-hold) circuit 814 and a de-track S-H circuit 813. In theon-track S-H circuit 814 and the de-track S-H circuit 813, the amplitudedifference Vp-Vb obtained from the on-track reproduced signal and theamplitude difference obtained from the de-track reproduced signal areheld with reference to an on-track timing signal 802 and a de-tracktiming signal 801, respectively. The on-track S-H circuit 814 and thede-track S-H circuit 813 output the amplitude Von of the on-trackreproduced signal and the amplitude Vde of the de-track reproducedsignal, respectively. The on-track timing signal 802 is a referencetiming signal indicating the course of on-track reproduction. Thede-track timing signal 801 is a reference timing signal indicating thecourse of de-track reproduction. Each of the two timing signals 802 and801 is issued from the main controller 103. The amplitude Vde isamplified by a predetermined gain G by a variable gain amplifier 815,and then the amplitudes G·Vde and Von are given to a subtracter 816. Thesubtracter 816 calculates the difference Von−G·Vde, so that acalculation result is transmitted as a test-write evaluation result 803to the main controller. If recording is performed by use of recordingpower which is such that the ratio of Von to Vde takes a predeterminedvalue G, that is, which is such that the difference value Von−G·Vdebecomes zero, in the same manner as in FIG. 6, a mark having a constantwidth can be formed extremely accurately. Hence, the distance betweenadjacent tracks of an optical disk can be reduced, so that theinformation recording apparatus can be improved in storage capacity andreliability.

[0039]FIG. 10 is a third explanatory view showing a furtherrecording/reproducing method applied to the test-write zone by theapparatus explained above with reference to FIG. 1. On a disk which is arecording medium, grooves 1004 are formed at regular intervals in aradial direction of the disk so that the grooves 1004 divide a surfaceof the disk into tracks and generate a tracking servo signal by acontinuous servo method. Address pits 1000 for holding addressinformation are formed at regular intervals in each track, so that eachtrack is further divided into sectors 1006 as minimum rewriting units.In a recording mode, VFO marks 1001 serving as a recording/reproducingtiming reference are formed just after the address pits 1000, and userdata or test-write marks 1005 are formed after the VFO marks 1001.First, in a test-write recording mode, adjacent tracks n−1, n and n+1are erased. Then, a test-write mark 1005 is formed on each track so asto be over the whole of a sector 1006. The test-write mark 1005 formedon each track may violate the conversion rule of the encoder 104 (thatis, the test-write mark 1005 may exceed the run-length limitation). Thisis no problem for the recording condition optimizing operation. It israther preferable that the mark is as long as possible so that the markextends over the whole of the sector 1006. In the test-write recordingmode, the optical spot is (on-track) controlled to scan the center ofeach track as represented by the on-track optical spot 1003. In FIG. 10,each of the arrows denotes the scanning direction and center position ofthe optical spot. Then, in a test-write evaluation mode, afterreproduction is performed in the same servo condition as in thetest-write recording mode so that the optical spot scans the center ofthe track, (off-track) reproduction is performed while tracking controlis stopped so that the optical spot performs scanning across tracks.Although the case of off-track reproduction is shown now, vibrationcontrol may be performed so that the optical spot makes a reciprocatingmotion across tracks in a direction perpendicular to the track inaddition to scanning (main scanning) in the tracking direction.

[0040]FIG. 11 is a diagram showing an example of the configuration of areproduction signal evaluation circuit corresponding to FIG. 10. FIG. 12is a diagram showing the operation of the reproduction signal evaluationcircuit depicted in FIG. 11. First, after a high-frequency component isremoved by a low pass filter 1110, a reproduced signal 1100 such as areproduced magneto-optical signal is supplied to a D/A converter 1111and digitized therein. An output of the D/A converter 1111 is suppliedto a saturation level latch 1112, an initial level latch 1113 and atest-write level latch 1114. The saturation level latch 1112 holds thereproduced signal average level Vs in the case of on-track reproductionof the test-write mark 1005. The initial level latch 1113 holds thereproduced signal average level Vi in the case of on-track reproductionon the initialized test-write zone. The test-write level latch 1114holds the reproduced signal average level Vt in the case wherereproduction is performed so that the optical spot performs scanningacross tracks. The outputs Vs, Vi and Vt of the respective level latches1112, 1113 and 1114 are supplied to subtracters 1115 and 1116, so thatdifferences Vs−Vi and Vt−Vi are calculated by the subtracters 1115 and1116, respectively. Then, these calculation results are given to adivider 1117, so that the ratio (Vt−Vi)/(Vs−Vi) is finally calculated.The calculation result is transmitted as an evaluation result to themain controller.

[0041]FIG. 13 is a graph showing a reproduction signal evaluation methodincluded in the recording condition optimizing method explained abovewith reference to FIGS. 10 to 12. Recording power is optimized by therecording condition optimizing operation in accordance with thefollowing procedure. That is, on-track reproduction and off-trackreproduction are performed by use of the test-write zone while recordingpower is changed, so that average levels Vs, Vi and Vt of signalsreproduced from the test-write mark are detected. The difference Vs−Viequivalent to the signal amplitude in the case of on-track reproductionbegins to increase at recording commencing power and increasescontinuously as the mark width increases. However, after the mark widthbecomes approximately equal to the diameter of the optical spot, theamplitude little changes even if the recording power is increased. Thisis because the difference value Vs−Vi is the mirror of the mark width.On the other hand, the average level Vt in the case of off-trackreproduction begins to increase gradually from the initial value Vi atrecording commencing power and increases as the mark width increases.However, after marks on adjacent tracks come into contact with eachother, the level Vt is saturated with the same value as the level Vs.This is because the difference value Vt−Vi is the mirror of the distancebetween marks on adjacent tracks. Hence, if recording is performed withrecording power which is such that the ratio of Vt−Vi to Vs−Vi takes apredetermined value, a mark having a constant width can be formedextremely accurately. Hence, the distance between adjacent tracks of anoptical disk can be reduced, so that the information recording apparatuscan be improved in storage capacity and reliability.

[0042]FIG. 14 is a fourth explanatory view showing a furtherrecording/reproducing method applied to the test-write zone by theapparatus explained above with reference to FIG. 1. On a disk which is arecording medium, grooves 1405 are formed at regular intervals in aradial direction of the disk. The grooves 1405 are used to divide asurface of the disk into tracks and generate a tracking servo signal bya continuous servo method. Address pits 1400 for holding addressinformation are formed at regular intervals in each track, so that eachtrack is divided into sectors 1407 as minimum rewriting units. In arecording mode, VFO marks 1401 serving as a recording/reproducing timingreference are formed just after the address pits 1400, and user data ortest-write marks 1406 are formed after the VFO marks 1401. In atest-write recording mode, adjacent tracks n−1, n and n+1 are firsterased and then test-write marks 1406 are formed at suitable periods ontracks n−1 and n+1. Taking into account the necessity of measuring themark width accurately while avoiding timing error between recording andreproduction and the influence of leading and trailing edges of eachmark at the time of detection of the mark, it is preferable that thelength of each test-write mark 1406/space in the tracks n−1 and n+1 ismade to be not smaller than the diameter of the optical spot and aslarger as possible. Particularly when a light intensity modulationmethod is used, there is a possibility that the width of the leadingedge of the mark in which accumulation of recording energy is notconverged is different from the width of the trailing edge of the markin which accumulation of recording energy is converged. It is preferablefrom this point of view that the mark is set to be as long as possibleto measure the mark width accurately. Taking into account the frequencycharacteristic of the recording/reproducing channel, the followingresponse of the PLL for generating a recording/reproducing timingsignal, etc., it is, however, undesirable that a mark/space which is toolong for recording/reproducing user data actually is used as thetest-write mark 1406/space in the tracks n−1 and n+1. To sum up, hence,it is most preferable that the longest mark/space allowable in the scopeof the conversion rule of the encoder 104 is used as the test-write mark1406 and space in the tracks n−1 and n+1. When, for example, theconversion rule of the encoder 104 is (1,7) modulation, and informationis subjected to mark edge recording (NRZI modulation) after conversion,the length of mark/space to be used for recording/reproducing user dataactually is in a range of from 2 to 8 channel bits. Hence, in this case,it is most preferable that the length of test-write mark 1406/space ineach of the tracks n−1 and n+1 is 8 channel bits. In the test-writerecording mode, the optical spot is controlled to scan the center ofeach track as represented by the mark-recorded-track optical spot 1402.In FIG. 14, each of the arrows denotes the scanning direction and centerposition of the optical spot. Then, in a test-write evaluation mode,after reproduction is performed in the same servo condition as in thetest-write recording mode so that the optical spot scans the center ofthe track n−1 or n+1, the servo condition is changed. That is, theoptical spot scans the center of the track n as represented by themark-adjacent-track optical spot 1404.

[0043]FIG. 15 is a diagram showing an example of the configuration of areproduction signal evaluation circuit corresponding to FIG. 14. FIG. 16is a diagram showing the operation of the reproduction signal evaluationcircuit depicted in FIG. 15. First, a reproduced signal 1500 such as areproduced magneto-optical signal is supplied to a peak detectioncircuit 1511 and a bottom detection circuit 1510, and converted into apeak envelope signal Vp and a bottom envelope signal Vb. The signals Vpand Vb are supplied to a subtracter 1512 to form a reproduced signalamplitude Vp−Vb. The value Vp−Vb is supplied to a mark-recorded-trackS-H circuit 1514 and a mark-adjacent-track S-H circuit 1513. In themark-recorded-track S-H circuit 1514 and the mark-adjacent-track S-Hcircuit 1513, the value Vp−Vb obtained from the reproduced signal in thecase of reproduction from a track having recorded test-write marks 1406and the value Vp−Vb obtained from the reproduced signal in the case ofreproduction from a track adjacent to the test-write marks 1406 are heldwith reference to the mark-recorded-track timing signal 1502 and themark-adjacent-track timing signal 1501, respectively. Themark-recorded-track S-H circuit 1514 and the mark-adjacent-track S-Hcircuit 1513 output the reproduced signal amplitude Von in the case ofreproduction from the track having the recorded test-write marks 1406and the reproduced signal amplitude Vne in the case of reproduction fromthe track adjacent to the test-write marks 1406, respectively. Themark-recorded-track timing signal 1502 is a reference timing signalindicating reproduction from a track having recorded test-write marks1406. The mark-adjacent-track timing signal 1501 is a reference timingsignal indicating reproduction from a track adjacent to the test-writemarks 1406. The two reference timing signals are issued from the maincontroller 103. After the amplitude Von is attenuated by a predeterminedattenuation factor G by a variable attenuator 1516, the values Von/G andVne are given to a subtracter 1515. The subtracter 1515 calculates thedifference Von/G−Vne. The calculation result is transmitted as atest-write evaluation result 1503 to the main controller. If recordingis performed with recording power which is such that the ratio of Von toVne takes a predetermined value, that is, which is such that thedifference value Von/G−Vne becomes zero, a mark having a constant widthcan be formed extremely accurately. Hence, the distance between adjacenttracks of an optical disk can be reduced, so that the informationrecording apparatus can be improved in storage capacity and reliability.

[0044] Furthermore, this invention does not intend to limit therecording method, and gist of the present invention is also effectivefor an information recording apparatus based on not only so-called“light intensity modulation method”, but also so-called “magnetic fieldmodulation method” or “laser-strobe magnetic field modulation method.”

[0045] According to the present invention, in an information recordingapparatus for recording information by irradiation of energy to arecording medium to cause a local physical change in the recordingmedium, marks carrying information can be formed to a desired shapewhich is neither too large nor too small. Hence, it becomes unnecessaryto secure the margin of the track width for increase of crosstalk andcross-erase. Hence, the distance between adjacent tracks can be reduced,so that recording surface density can be enhanced. At the same time,high reliability of the recording/reproducing operation is achieved, sothat the size of the information recording apparatus and the size of therecording medium can be reduced. Hence, it is advantageous in terms ofcost.

What is claimed:
 1. An information recording apparatus for recordinginformation on a recording medium by supplying said recording mediumwith energy to form marks different in physical property fromnon-recorded portions, comprising: an energy generation means forgenerating recording energy; a position control means for controlling aposition of supply to said recording medium with an output of saidenergy generation means; a drive means for driving said energygeneration means; a switching means for switching information based onuser data and test information to supply these two kinds of informationselectively to said drive means; a reading means for reading said marksrecorded on said recording medium; a vibration means for vibrating saidreading means in a direction perpendicular to a main scanning directionon said recording medium; an evaluation means for evaluating areproduced signal obtained by said reading means; and a recordingcondition control means for controlling a recording condition on thebasis of an evaluation result obtained by said evaluation means.
 2. Aninformation recording apparatus for recording information on a recordingmedium by supplying said recording medium with energy to form marksdifferent in physical property from non-recorded portions, comprising:an energy generation means for generating recording energy; a positioncontrol means for controlling a position of supply to said recordingmedium with an output of said energy generation means; a drive means fordriving said energy generation means; a conversion means for convertinguser data in accordance with a predetermined rule; a switching means forswitching information based on conversion of said user data by saidconversion means and test information to supply these two kinds ofinformation selectively to said drive means; a reading means for readingsaid marks recorded on said recording medium; an evaluation means forevaluating a reproduced signal obtained by said reading means; and arecording condition control means for controlling a recording conditionon the basis of an evaluation result obtained by said evaluation means,wherein, when said test information is supplied to said drive means soas to be recorded, specially prepared test information against saidpredetermined rule is used, and wherein when reproducing a mark beingrecorded said test information, a control operation of said positioncontrol means is changed to a condition of recording said testinformation.
 3. An information recording apparatus according to claim 2,wherein said specially prepared test information contains a longer runthan a run-length limit of said conversion means.
 4. An informationrecording apparatus for recording information on a recording medium bysupplying said recording medium with energy to form marks different inphysical property from non-recorded portions, comprising: an energygeneration means for generating recording energy; position control meansfor controlling a position of supply to said recording medium with anoutput of said energy generation means; drive means for driving saidenergy generation means; switching means for switching information basedon user data and test information to supply these two kinds ofinformation selectively to said drive means; reading means for readingsaid marks recorded on said recording medium; evaluation means forevaluating a reproduced signal obtained by said reading means; andrecording condition control means for controlling a recording conditionon the basis of an evaluation result obtained by said evaluation means,wherein, when said test information is supplied to said drive means soas to be recorded, different kinds of test information are recorded on aplurality of tracks, and wherein when reproducing a mark being recordedsaid test information, a control operation of said position controlmeans is changed to a condition of recording said test information.